Dicing tape-integrated wafer back surface protective film

ABSTRACT

The present invention provides a dicing tape-integrated wafer back surface protective film including: a dicing tape including a base material and a pressure-sensitive adhesive layer formed on the base material; and a wafer back surface protective film formed on the pressure-sensitive adhesive layer of the dicing tape, in which the wafer back surface protective film is colored. It is preferable that the colored wafer back surface protective film has a laser marking ability. The dicing tape-integrated wafer back surface protective film can be suitably used for a flip chip-mounted semiconductor device.

FIELD OF THE INVENTION

This is a Continuation of application Ser. No. 13/534,269 filed Jun. 27,2012, which is a Continuation of application Ser. No. 12/696,135, filedJan. 29, 2010, now, U.S. Pat. No. 8,237,294, issued Aug. 7, 2012, whichclaims priority from JP 2009-020460 filed Jan. 30, 2009 and JP2009-25115 filed Oct. 30, 2009, the contents of all of which areincorporated herein by reference in their entirety.

The present invention relates to a dicing tape-integrated wafer backsurface protective film. A dicing tape-integrated wafer back surfaceprotective film is used for protecting a back surface of a chip-shapedworkpiece (such as a semiconductor chip) and enhancing strength.Moreover, the invention relates to a semiconductor device using thedicing tape-integrated wafer back surface protective film and a processfor producing the device.

BACKGROUND OF THE INVENTION

Recently, thinning and miniaturization of a semiconductor device and itspackage have been increasingly demanded. Therefore, as the semiconductordevice and its package, those in which a semiconductor chip (chip-shapedworkpiece) is fixed to a substrate in a form where a circuit face of thesemiconductor chip is opposed to an electrode-formed face of thesubstrate (one produced by flip chip bonding; it may be referred as aflip chip-mounted semiconductor device) have been widely utilized. Insuch a semiconductor device or the like, the back surface of thesemiconductor chip (chip-shaped workpiece) is protected with aprotective film to inhibit the damage of the semiconductor chip in somecases (see, for example, Patent Documents 1 to 10).

-   Patent Document 1: JP-A-2008-166451-   Patent Document 2: JP-A-2008-006386-   Patent Document 3: JP-A-2007-261035-   Patent Document 4: JP-A-2007-250970-   Patent Document 5: JP-A-2007-158026-   Patent Document 6: JP-A-2004-221169-   Patent Document 7: JP-A-2004-214288-   Patent Document 8: JP-A-2004-142430-   Patent Document 9: JP-A-2004-072108-   Patent Document 10: JP-A-2004-063551

SUMMARY OF THE INVENTION

However, the attachment of a back surface protective film for protectinga back surface of a semiconductor chip to the back surface of thesemiconductor chip obtained by dicing a semiconductor wafer in a dicingstep results in the addition of a step for the attachment, so that thenumber of steps increases and cost and the like increase. Moreover,owing to the thinning, the semiconductor chip may be damaged in somecases in a picking-up step of the semiconductor chip after the dicingstep. Thus, it is desired to reinforce the semiconductor wafer orsemiconductor chip until the picking-up step.

In consideration of the foregoing problem, an object of the presentinvention is to provide a dicing tape-integrated wafer back surfaceprotective film capable of being utilized from the dicing step of thesemiconductor wafer to the flip chip bonding step of the semiconductorchip. Moreover, another object of the invention is to provide a dicingtape-integrated wafer back surface protective film capable of exhibitingan excellent holding force in the dicing step of the semiconductor chipand capable of exhibiting a marking property and an appearance propertyafter the flip chip bonding step of the semiconductor chip.

As a result of intensive investigations for solving the above-mentionedconventional problems, the present inventors have found that, when acolored wafer back surface protective film is laminated on apressure-sensitive adhesive layer of a dicing tape having a basematerial and the pressure-sensitive adhesive layer to form the dicingtape and the wafer back surface protective film in an integratedfashion, the laminate (dicing tape-integrated wafer back surfaceprotective film) where the dicing tape and the wafer back surfaceprotective film are formed in an integrated fashion can be utilized fromthe dicing step of the semiconductor wafer to the flip chip bonding stepof the semiconductor chip as well as an excellent holding force can beexhibited in the dicing step of the semiconductor wafer and a markingproperty and an appearance property can be exhibited after the flip chipbonding step of the semiconductor chip, thereby accomplishing theinvention.

Namely, the present invention provides a dicing tape-integrated waferback surface protective film including: a dicing tape including a basematerial and a pressure-sensitive adhesive layer formed on the basematerial; and a wafer back surface protective film formed on thepressure-sensitive adhesive layer of the dicing tape, in which the waferback surface protective film is colored.

As above, since the dicing tape-integrated wafer back surface protectivefilm of the invention is formed in a form where the wafer back surfaceprotective film is integrated with the dicing tape including the basematerial and the pressure-sensitive adhesive layer as well as the waferback surface protective film is colored, a workpiece can be held andeffectively diced by attaching the dicing tape-integrated wafer backsurface protective film to the workpiece (semiconductor wafer) at dicingof the wafer (semiconductor wafer). Moreover, after the workpiece isdiced to form a chip-shaped workpiece (semiconductor chip), by peelingthe chip-shaped workpiece together with the colored wafer back surfaceprotective film from the pressure-sensitive adhesive layer of the dicingtape, the chip-shaped workpiece whose back surface is protected can beeasily obtained and also the marking property, appearance property, andthe like of the back surface of the chip-shaped workpiece can beeffectively improved.

Furthermore, in the dicing tape-integrated wafer back surface protectivefilm of the invention, since the dicing tape and the colored wafer backsurface protective film are formed in an integrated fashion as mentionedabove, the colored wafer back surface protective film can also beattached at the time when the dicing tape is attached to the backsurface of the semiconductor wafer before the dicing step and thus astep of attaching the wafer back surface protective film alone (waferback surface protective film-attaching step) is not necessary. Inaddition, in the subsequent dicing step and picking-up step, since thecolored wafer back surface protective film is attached on the backsurface of the semiconductor wafer or the back surface of thesemiconductor chip formed by dicing, the semiconductor wafer or thesemiconductor chip can be effectively protected and thus the damage ofthe semiconductor chip can be suppressed or prevented in the dicing stepor subsequent steps (the picking-up step, etc.).

In the present invention, the colored wafer back surface protective filmpreferably has a laser marking ability. In addition, the dicingtape-integrated wafer back surface protective film can be suitably usedfor a flip chip-mounted semiconductor device.

The present invention also provides a process for producing asemiconductor device using a dicing tape-integrated wafer back surfaceprotective film, the process including steps of: attaching a workpieceonto the colored wafer back surface protective film of theabove-mentioned dicing tape-integrated wafer back surface protectivefilm, dicing the workpiece to form a chip-shaped workpiece, peeling thechip-shaped workpiece from the pressure-sensitive adhesive layer of thedicing tape together with the colored wafer back surface protectivefilm, and fixing the chip-shaped workpiece to an adherend by flip chipbonding.

In addition, the present invention further provides a flip chip-mountedsemiconductor device, which is manufactured using the above-mentioneddicing tape-integrated wafer back surface protective film, in which thesemiconductor device including a chip-shaped workpiece and the waferback surface protective film of the dicing tape-integrated wafer backsurface protective film attached to a back surface of the chip-shapedworkpiece.

Since the dicing tape and the wafer back surface protective film areformed in an integrated fashion as well as the wafer back surfaceprotective film is colored, the dicing tape-integrated wafer backsurface protective film of the invention can be utilized from the dicingstep of the semiconductor wafer to the flip chip bonding step of thesemiconductor chip. Specifically, the dicing tape-integrated wafer backsurface protective film of the invention can exhibit an excellentholding force in the dicing step of the semiconductor wafer and also canexhibit a marking property and an appearance property during and afterthe flip chip bonding step of the semiconductor chip. Moreover, in theflip chip bonding step and the like, since the back surface of thesemiconductor ship is protected with the colored wafer back surfaceprotective film, breakage, chipping, warp, and the like of thesemiconductor chip can be effectively suppressed or prevented. Needlessto say, the dicing tape-integrated wafer back surface protective film ofthe invention can effectively exhibit functions thereof in steps otherthan the steps from the dicing step to the flip chip bonding step of thesemiconductor chip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view showing one embodiment of adicing tape-integrated wafer back surface protective film of theinvention.

FIGS. 2A to 2D are cross-sectional schematic views showing oneembodiment of a process for producing a semiconductor device using adicing tape-integrated wafer back surface protective film of theinvention.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

1 dicing tape-integrated wafer back surface protective film 2 coloredwafer back surface protective film 3 dicing tape 31 base material 32pressure-sensitive adhesive layer 4 semiconductor wafer (workpiece) 5semiconductor chip (chip-shaped workpiece) 51 bump formed at circuitface of semiconductor chip 5 6 adherend 61 conductive material forconjunction adhered to connecting pad of adherend 6

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention is described with reference toFIG. 1 but the invention is not restricted to this embodiment. FIG. 1 isa cross-sectional schematic view showing one embodiment of a dicingtape-integrated wafer back surface protective film of the invention. InFIG. 1, 1 is a dicing tape-integrated wafer back surface protectivefilm, 2 is a wafer back surface protective film which is colored(sometimes referred to simply as a “colored wafer back surfaceprotective film”), 3 is a dicing tape, 31 is a base material, and 32 isa pressure-sensitive adhesive layer.

Incidentally, in the figures in the present specification, parts thatare unnecessary for the description are not given, and there are partsshown by magnifying, minifying, etc. in order to make the descriptioneasy.

As shown in FIG. 1, the dicing tape-integrated wafer back surfaceprotective film 1 has a constitution that the colored wafer back surfaceprotective film 2 is formed on the pressure-sensitive adhesive layer 32of the dicing tape 3 having the base material 31 and thepressure-sensitive adhesive layer 32 formed on the base material 31. Inthis regard, the surface of the colored wafer back surface protectivefilm 2 (surface to be attached to the back surface of the wafer) may beprotected with a separator or the like during the period until it isattached to the back surface of the wafer.

Incidentally, the dicing tape-integrated wafer back surface protectivefilm may have a constitution that the colored wafer back surfaceprotective film is formed on the pressure-sensitive adhesive layer ofthe dicing tape over the whole surface or may have a constitution thatthe colored wafer back surface protective film is partially formed. Forexample, as shown in FIG. 1, the dicing tape-integrated wafer backsurface protective film may have a constitution that the colored waferback surface protective film is formed, on the pressure-sensitiveadhesive layer of the dicing tape, only on the part to which thesemiconductor wafer is to be attached.

(Colored Wafer Back Surface Protective Film)

The colored wafer back surface protective film has a film shape. In thecut-processing step (dicing step) of cutting a workpiece (semiconductorwafer) attached on the colored wafer back surface protective film, thecolored wafer back surface protective film has a function of supportingthe workpiece with close adhesion thereto and, after the dicing step,has a function of protecting the back surface of the chip-shapedworkpiece (semiconductor chip) and exhibiting excellent marking propertyand appearance property after peeling the diced chip-shaped workpiecetogether with the colored wafer back surface protective film from thedicing tape. As above, since the colored wafer back surface protectivefilm has an excellent marking property, marking can be performed toimpart various kinds of information such as literal information andgraphical information to the non-circuit face of the chip-shapedworkpiece or the non-circuit face of a semiconductor device using thechip-shaped workpiece by utilizing various marking methods such asprinting methods and laser marking methods through the colored waferback surface protective film. Moreover, by controlling the color of thecoloring, it becomes possible to observe the information (literalinformation, graphical information, etc.) imparted by the marking withan excellent visibility. Furthermore, since the colored wafer backsurface protective film is colored, the dicing tape and the coloredwafer back surface protective film can be easily distinguished from eachother and thus workability and the like can be improved.

Moreover, since the colored wafer back surface protective film has anexcellent appearance property, it becomes possible to provide asemiconductor device having a value-added appearance. For example, as asemiconductor device, it is possible to classify products thereof byusing different colors.

Incidentally, as the colored wafer back surface protective film, it isimportant to have close adhesiveness so that cut pieces are notscattered at the cut-processing of the workpiece.

As above, the colored wafer back surface protective film is used not fordie-bonding a semiconductor chip to a supporting member such as asubstrate but for protecting the back surface (non-circuit face) of asemiconductor chip to be flip chip mounted (or having been flip chipmounted) and has most suitable function and constitution therefor. Inthis regard, a die-bonding film to be used in the use application ofstrongly adhering the semiconductor chip to the supporting member suchas the substrate is an adhesive layer and is encapsulated with anencapsulating material, so that the film is not colored and also doesnot have a marking property (particularly, a laser marking ability).Therefore, the colored wafer back surface protective film has a functionor constitution different from that of the die-bonding film and thus itis not suitable to use the protective film as the die-bonding film.

In the invention, the colored wafer back surface protective film can beformed of a resin composition and is preferably constituted by a resincomposition containing a thermoplastic resin and a thermosetting resin.In this regard, the colored wafer back surface protective film may beconstituted by a thermoplastic resin composition using no thermosettingresin or may be constituted by a thermosetting resin composition usingno thermoplastic resin.

Examples of the thermoplastic resin include natural rubber, butylrubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetatecopolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acidester copolymers, polybutadiene resins, polycarbonate resins,thermoplastic polyimide resins, polyamide resins such 6-Nylon and6,6-Nylon, phenoxy resins, acrylic resins, saturated polyester resinssuch as PET (polyethylene terephthalate) and PBT (polybutyleneterephthalate), or fluorocarbon resins. The thermoplastic resin may beemployed singly or in a combination of two or more kinds. Among thesethermoplastic resins, acrylic resins containing only a small amount ofionic impurities, having a high heat resistance, and capable of securingreliability of a semiconductor element are preferable.

The acrylic resins are not particularly restricted, and examples thereofinclude polymers containing one kind or two or more kinds of esters ofacrylic acid or methacrylic acid having a straight chain or branchedalkyl group having 30 or less carbon atoms, preferably 4 to 18 carbonatoms as component(s). Namely, in the invention, the acrylic resin has abroad meaning also including a methacrylic resin. Examples of the alkylgroup include a methyl group, an ethyl group, a propyl group, anisopropyl group, an n-butyl group, a t-butyl group, an isobutyl group, apentyl group, an isopentyl group, a hexyl group, a heptyl group, a2-ethylhexyl group, an octyl group, an isooctyl group, a nonyl group, anisononyl group, a decyl group, an isodecyl group, an undecyl group, adodecyl group (lauryl group), a tridecyl group, a tetradecyl group, astearyl group, and an octadecyl group.

Moreover, other monomers for forming the acrylic resins (monomers otherthan the esters of acrylic acid or methacrylic acid having 30 or lesscarbon atoms) are not particularly restricted, and examples thereofinclude carboxyl group-containing monomers such as acrylic acid,methacrylic acid, carboxylethyl acrylate, carboxylpentyl acrylate,itaconic acid, maleic acid, fumaric acid, and crotonic acid; acidanhydride monomers such as maleic anhydride and itaconic anhydride;hydroxyl group-containing monomers such as 2-hydroxyethyl(meth)acrylate,2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate,6-hydroxyhexyl(meth)acrylate, 8-hydroxyoctyl(meth)acrylate,10-hydroxydecyl(meth)acrylate, 12-hydroxylauryl(meth)acrylate, and(4-hydroxymethylcyclohexyl)-methylacrylate; sulfonic acid-containingmonomers such as styrenesulfonic acid, allylsulfonic acid,2-(meth)acrylamido-2-methylpropanesulfonic acid,(meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and(meth)acryloyloxynaphthalenesulfonic acid; and phosphoric acidgroup-containing monomers such as 2-hydroxyethylacryloyl phosphate.

Such resins may be synthesized according to known methods orcommercially available products may be used.

Moreover, examples of the thermosetting resins include epoxy resins andphenol resins as well as amino resins, unsaturated polyester resins,polyurethane resins, silicone resins, and thermosetting polyimideresins. The thermosetting resin may be employed singly or in acombination of two or more kinds. As the thermosetting resin, an epoxyresin containing only a small amount of ionic impurities which corrodesemiconductor elements is suitable. Further, the phenol resin ispreferably used as a curing agent of the epoxy resins.

The epoxy resin is not particularly restricted and, for example, adifunctional epoxy resin or a polyfunctional epoxy resin such as abisphenol A type epoxy resin, a bisphenol F type epoxy resin, abisphenol S type epoxy resin, a brominated bisphenol A type epoxy resin,a hydrogenated bisphenol A type epoxy resin, a bisphenol AF type epoxyresin, a biphenyl type epoxy resin, a naphthalene type epoxy resin, afluorene type epoxy resin, a phenol novolak type epoxy resin, ano-cresol novolak type epoxy resin, a trishydroxyphenylmethane type epoxyresin and a tetraphenylolethane type epoxy resin, or an epoxy resin suchas a hydantoin type epoxy resin, a trisglycidylisocyanurate type epoxyresin or a glycidylamine type epoxy resin may be used.

As the epoxy resin, among those exemplified above, a novolak type epoxyresin, a biphenyl type epoxy resin, a trishydroxyphenylmethane typeepoxy resin, and a tetraphenylolethane type epoxy resin are preferable.This is because these epoxy resins have high reactivity with a phenolresin as a curing agent and are superior in heat resistance and thelike.

The epoxy resins may be synthesized according to known methods, orcommercially available products may be used.

Furthermore, the above-mentioned phenol resin acts as a curing agent ofthe epoxy resin, and examples thereof include novolak type phenol resinssuch as phenol novolak resins, phenol aralkyl resins, cresol novolakresins, tert-butylphenol novolak resins, and nonylphenol novolak resins;resol type phenol resins; and polyoxystyrenes such as poly-p-oxystyrene.The phenol resin may be employed singly or in a combination of two ormore kinds. Among these phenol resins, phenol novolak resins and phenolaralkyl resins are particularly preferable. This is because connectionreliability of the semiconductor device can be improved.

The phenol resin may be synthesized according to known methods orcommercially available products may be used.

The mixing ratio of the epoxy resin to the phenol resin is preferablymade, for example, such that the hydroxyl group in the phenol resinbecomes 0.5 to 2.0 equivalents per equivalent of the epoxy group in theepoxy resin component. It is more preferably 0.8 to 1.2 equivalents.That is, when the mixing ratio becomes outside the range, a curingreaction does not proceed sufficiently, and the characteristics of theepoxy resin cured product tends to deteriorate.

A thermal curing-accelerating catalyst for the epoxy resins and thephenol resins is not particularly restricted and can be suitablyselected from known thermal curing-accelerating catalysts and used. Thethermal curing-accelerating catalyst may be employed singly or in acombination of two or more kinds. As the thermal curing-acceleratingcatalyst, for example, an amine-based curing-accelerating catalyst, aphosphorus-based curing-accelerating catalyst, an imidazole-basedcuring-accelerating catalyst, a boron-based curing-acceleratingcatalyst, or a phosphorus-boron-based curing-accelerating catalyst canbe used.

In the invention, the colored wafer back surface protective film ispreferably formed of a resin composition containing an epoxy resin, aphenol resin, and an acrylic resin. Since these resins contain only asmall amount of ionic impurities and have a high heat resistance,reliability of the semiconductor element can be secured. The mixingratio in this case is not particularly restricted but, for example, themixing amount of the epoxy resin and the phenol resin can be suitablyselected from the range of 10 to 300 parts by weight based on 100 partsby weight of the acrylic resin component.

It is important that the colored wafer back surface protective film hasclose adhesiveness to the back surface (non-circuit-formed face) of thesemiconductor wafer. Such a colored wafer back surface protective filmhaving close adhesiveness can be, for example, formed of a resincomposition containing an epoxy resin. For crosslinking, apolyfunctional compound capable of reacting with a functional group orthe like at a molecular chain end of the polymer can be added as acrosslinking agent to the colored wafer back surface protective film.Owing to this constitution, a close adhesiveness under high temperaturecan be enhanced and an improvement of the heat resistance can beachieved.

The crosslinking agent is not particularly restricted and knowncrosslinking agents can be used. Specifically, as the crosslinkingagent, not only isocyanate-based crosslinking agents, epoxy-basedcrosslinking agents, melamine-based crosslinking agents, andperoxide-based crosslinking agents but also urea-based crosslinkingagents, metal alkoxide-based crosslinking agents, metal chelate-basedcrosslinking agents, metal salt-based crosslinking agents,carbodiimide-based crosslinking agents, oxazoline-based crosslinkingagents, aziridine-based crosslinking agents, amine-based crosslinkingagents, and the like may be mentioned. As the crosslinking agent, anisocyanate-based crosslinking agent or an epoxy-based crosslinking agentis suitable. The crosslinking agent may be employed singly or in acombination of two or more kinds.

Examples of the isocyanate-based crosslinking agents include loweraliphatic polyisocyanates such as 1,2-ethylene diisocyanate,1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclicpolyisocyanates such as cyclopentylene diisocyanate, cyclohexylenediisocyanate, isophorone diisocyanate, hydrogenated tolylenediisocyanate, and hydrogenated xylylene diisocyanate; and aromaticpolyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylenediisocyanate. In addition, a trimethylolpropane/tolylene diisocyanatetrimer adduct [trade name “COLONATE L” manufactured by NipponPolyurethane Industry Co., Ltd.], a trimethylolpropane/hexamethylenediisocyanate trimer adduct [trade name “COLONATE HL” manufactured byNippon Polyurethane Industry Co., Ltd.], and the like are also used.Moreover, examples of the epoxy-based crosslinking agents includeN,N,N′,N′-tetraglycidyl-m-xylenediamine, diglycidylaniline,1,3-bis(N,N-glycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidylether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidylether, propylene glycol diglycidyl ether, polyethylene glycol diglycidylether, polypropylene glycol diglycidyl ether, sorbitol polyglycidylether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether,polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether,trimethylolpropnane polyglycidyl ether, adipic acid diglycidyl ester,o-phthalic acid diglycidyl ester,triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcin diglycidyl ether,and bisphenol-S-diglycidyl ether, and also epoxy-based resins having twoor more epoxy groups in the molecule.

The amount of the crosslinking agent is not particularly restricted andcan be appropriately selected depending on the degree of thecrosslinking. Specifically, it is preferable that the amount of thecrosslinking agent is, for example, 0.05 to 7 parts by weight based on100 parts by weight of the polymer component (particularly, a polymerhaving a functional group at the molecular chain end). When the amountof the crosslinking agent is within the range of 0.05 to 7 parts byweight based on 100 parts by weight of the polymer component, a closeadhesiveness and a cohesion property can be exhibited at a high level.

In the invention, instead of the use of the crosslinking agent ortogether with the use of the crosslinking agent, it is also possible toperform the crosslinking treatment by irradiation with an electron beamor ultraviolet light.

In the invention, the colored wafer back surface protective film iscolored. Namely, the colored wafer back surface protective film iscolored and is not colorless or transparent. In the colored wafer backsurface protective film, the color shown by coloring is not particularlyrestricted but, for example, is preferably dark color such as black,blue, or red color, and black color is more preferable.

In the invention, dark color basically means a dark color having L*,defined in L*a*b* color space, of 60 or smaller (from 0 to 60),preferably 50 or smaller (from 0 to 50), and more preferably 40 orsmaller (from 0 to 40).

Moreover, black color basically means a black-based color having L*,defined in L*a*b* color space, of 35 or smaller (from 0 to 35),preferably 30 or smaller (from 0 to 30), and more preferably 25 orsmaller (from 0 to 25). In this regard, in the black color, each of a*and b*, defined in the L*a*b* color space, can be suitably selectedaccording to the value of L*. For example, both of a* and b* are withinthe range of preferably from −10 to 10, more preferably from −5 to 5,and further preferably −3 to 3 (particularly 0 or about 0).

In the invention, L*, a* and b* defined in the L*a*b* color space can bedetermined by a measurement with a color difference meter (trade name“CR-200” manufactured by Minolta Ltd; color difference meter). TheL*a*b* color space is a color space recommended by the CommissionInternationale de l'Eclairage (CIE) in 1976, and means a color spacecalled CIE1976(L*a*b*) color space. Also, the L*a*b* color space isdefined in Japanese Industrial Standards in JIS Z8729.

At coloring of the colored wafer back surface protective film, accordingto an objective color, a colorant (coloring agent) can be used. As sucha colorant, various dark-colored colorants such as black-coloredcolorants, blue-colored colorants, and red-colored colorants can besuitably used and black-colored colorants are more suitable. Thecolorant may be any of pigments and dyes. The colorant may be employedsingly or in combination of two or more kinds. In this regard, as thedyes, it is possible to use any forms of dyes such as acid dyes,reactive dyes, direct dyes, disperse dyes, and cationic dyes. Moreover,also with regard to the pigments, the form thereof is not particularlyrestricted and can be suitably selected and used among known pigments.

The black-colored colorant is not particularly restricted and can be,for example, suitably selected from inorganic black-colored pigments andblack-colored dyes. Moreover, the black-colored colorant may be acolorant mixture in which a cyan-colored colorant (blue-green colorant),a magenta-colored colorant (red-purple colorant), and a yellow-colorantcolorant (yellow colorant). The black-colored colorant may be employedsingly or in a combination of two or more kinds. Of course, theblack-colored colorant may be used in combination with a colorant of acolor other than black.

Specific examples of the black-colored colorant include carbon black(such as furnace black, channel black, acetylene black, thermal black,or lamp black), graphite, copper oxide, manganese dioxide, anilineblack, perylene black, titanium black, cyanine black, active charcoal,ferrite (such as non-magnetic ferrite or magnetic ferrite), magnetite,chromium oxide, iron oxide, molybdenum disulfide, a chromium complex, acomposite oxide type black pigment, and an anthraquinone type organicblack pigment.

As the black-colored colorant, black-colored dyes such as C.I. SolventBlack 3, 7, 22, 27, 29, 34, 43, 70, C.I. Direct Black 17, 19, 22, 32,38, 51, 71, C.I. Acid Black 1, 2, 24, 26, 31, 48, 52, 107, 109, 110,119, 154, and C.I. Disperse Black 1, 3, 10, 24; black-colored pigmentssuch as C.I. Pigment Black 1, 7; and the like can be utilized.

As such black-colored colorants, for example, trade name “Oil Black BY”,trade name “Oil Black BS”, trade name “Oil Black HBB”, trade name “OilBlack 803”, trade name “Oil Black 860”, trade name “Oil Black 5970”,trade name “Oil Black 5906”, trade name “Oil Black 5905” (manufacturedby Orient Chemical Industries Co., Ltd.), and the like are commerciallyavailable.

Examples of colorants other than the black-colored colorant includecyan-colored colorants, magenta-colored colorants, and yellow-coloredcolorants.

Examples of the cyan-colored colorants include cyan-colored dyes such asC.I. Solvent Blue 25, 36, 60, 70, 93, 95; C.I. Acid Blue 6 and 45;cyan-colored pigments such as C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2,15:3, 15:4, 15:5, 15:6, 16, 17, 17:1, 18, 22, 25, 56, 60, 63, 65, 66;C.I. Vat Blue 4, 60; and C.I. Pigment Green 7.

Moreover, among the magenta colorants, examples of magenta-colored dyeinclude C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 52, 58, 63,81, 82, 83, 84, 100, 109, 111, 121, 122; C.I. Disperse Red 9; C.I.Solvent Violet 8, 13, 14, 21, 27; C.I. Disperse Violet 1; C.I. Basic Red1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37,38, 39, 40; C.I. Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27 and28.

Among the magenta-colored colorants, examples of magenta-colored pigmentinclude C.I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 42,48:1, 48:2, 48:3, 48:4, 49, 49:1, 50, 51, 52, 52:2, 53:1, 54, 55, 56,57:1, 58, 60, 60:1, 63, 63:1, 63:2, 64, 64:1, 67, 68, 81, 83, 87, 88,89, 90, 92, 101, 104, 105, 106, 108, 112, 114, 122, 123, 139, 144, 146,147, 149, 150, 151, 163, 166, 168, 170, 171, 172, 175, 176, 177, 178,179, 184, 185, 187, 190, 193, 202, 206, 207, 209, 219, 222, 224, 238,245; C.I. Pigment Violet 3, 9, 19, 23, 31, 32, 33, 36, 38, 43, 50; C.I.Vat Red 1, 2, 10, 13, 15, 23, 29 and 35.

Moreover, examples of the yellow-colored colorants includeyellow-colored dyes such as C.I. Solvent Yellow 19, 44, 77, 79, 81, 82,93, 98, 103, 104, 112, and 162; yellow-colored pigments such as C.I.Pigment Orange 31, 43; C.I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11,12, 13, 14, 15, 16, 17, 23, 24, 34, 35, 37, 42, 53, 55, 65, 73, 74, 75,81, 83, 93, 94, 95, 97, 98, 100, 101, 104, 108, 109, 110, 113, 114, 116,117, 120, 128, 129, 133, 138, 139, 147, 150, 151, 153, 154, 155, 156,167, 172, 173, 180, 185, 195; C.I. Vat Yellow 1, 3, and 20.

Various colorants such as cyan-colored colorants, magenta-coloredcolorants, and yellow-colorant colorants may be employed singly or in acombination of two or more kinds, respectively. In this regard, in thecase that two or more kinds of various colorants such as cyan-coloredcolorants, magenta-colored colorants, and yellow-colorant colorants areused, the mixing ratio (or blending ratio) of these colorants is notparticularly restricted and can be suitably selected according to thekind of each colorant, an objective color, and the like.

Incidentally, in the case that the black-colored colorant is a colorantmixture formed by mixing a cyan-colored colorant, a magenta-coloredcolorant and a yellow-colored colorant, each of the cyan-coloredcolorant, the magenta-colored colorant and the yellow-colored colorantmay be used singly or in a combination of two or more kinds. The mixingratio (or blending ratio) of the cyan-colored colorant, themagenta-colored colorant and the yellow-colored colorant in the colorantmixture is not particularly restricted as long as a black-based color(e.g., a black-based color having L*, a*, and b*, defined in L*a*b*color space, within the above ranges) can be exhibited, and may besuitably selected according to the type of each colorant and the like.The contents of the cyan-colored colorant, the magenta-colored colorantand the yellow-colored colorant in the colorant mixture can be suitablyselected, for example, within a range, with respect to the total amountof the colorants, of cyan-colored colorant/magenta-coloredcolorant/yellow-colored colorant=10-50% by weight/10-50% byweight/10-50% by weight (preferably 20-40% by weight/20-40% byweight/20-40% by weight).

The content of the colorant can be suitably selected from a range of 0.1to 10% by weight in the resin composition which forms the colored waferback surface protective film (excluding solvent(s)) and is preferablyfrom 0.5 to 8% by weight and more preferably from 1 to 5% by weight.

In this regard, into the colored wafer back surface protective film,other additives can be suitably blended according to the necessity.Examples of the other additives include, in addition to a filler, aflame retardant, a silane-coupling agent, and an ion-trapping agent, anextender, an antiaging agent, an antioxidant, and a surfactant.

The filler may be any of an inorganic filler and an organic filler butan inorganic filler is suitable. By blending a filler such as aninorganic filler, imparting of electric conductivity to the coloredwafer back surface protective film, improvement of the thermalconductivity of the colored wafer back surface protective film, controlof elastic modulus of the colored wafer back surface protective film,and the like can be achieved. In this regard, the colored wafer backsurface protective film may be electrically conductive ornon-conductive. Examples of the inorganic filler include variousinorganic powders composed of silica, clay, gypsum, calcium carbonate,barium sulfate, alumina oxide, beryllium oxide, ceramics such assilicone carbide and silicone nitride, metals or alloys such asaluminum, copper, silver, gold, nickel, chromium, lead, tin, zinc,palladium, and solder, carbon, and the like. The filler may be employedsingly or in a combination of two or more kinds. Particularly, thefiller is suitably silica and more suitably fused silica. The averageparticle diameter of the inorganic filler is preferably within the rangeof 0.1 to 80 μm. The average particle diameter of the inorganic fillercan be measured by a laser diffraction-type particle size distributionmeasurement apparatus.

The blending amount of the filler (e.g., inorganic filler) may be 150parts by weight or less (0 to 150 parts by weight) or may be 100 partsby weight or less (0 to 100 parts by weight) based on 100 parts byweight of the total amount of the resin components. In the invention,the blending amount of the filler is preferably 80 parts by weight orless (0 to 80 parts by weight) and more preferably 0 to 70 parts byweight based on 100 parts by weight of the total amount of the resincomponents.

Examples of the flame retardant include antimony trioxide, antimonypentoxide, and brominated epoxy resins. The flame retardant may beemployed singly or in a combination of two or more kinds. Examples ofthe silane coupling agent includeβ-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane, andγ-glycidoxypropylmethyldiethoxysilane. The silane coupling agent may beemployed singly or in a combination of two or more kinds. Examples ofthe ion-trapping agent include hydrotalcites and bismuth hydroxide. Theion-trapping agent may be employed singly or in a combination of two ormore kinds.

The colored wafer back surface protective film can be, for example,formed by utilizing a commonly used method including mixing athermosetting resin such as an epoxy resin and/or a thermoplastic resinsuch as an acrylic resin, a colorant (coloring agent), and optionalsolvent and other additives to prepare a resin composition, followed byforming it to a film-shaped layer. Specifically, a film-shaped layer asthe colored wafer back surface protective film can be formed, forexample, by a method including applying the resin composition on thepressure-sensitive adhesive layer of the dicing tape, a method includingapplying the resin composition on an appropriate separator (such asrelease paper) to form a resin layer and then transferring(transcribing) it on the pressure-sensitive adhesive layer of the dicingtape, and the like method.

In this regard, in the case that the colored wafer back surfaceprotective film is formed of a resin composition containing athermosetting resin such as an epoxy resin, the colored wafer backsurface protective film is in a state where the thermosetting resin isuncured or partially cured at a stage before the film is applied to asemiconductor wafer. In this case, after it is applied to thesemiconductor wafer (specifically, usually, at the time when theencapsulating material is cured in the flip chip bonding step), thethermosetting resin in the colored wafer back surface protective film iscompletely or almost completely cured.

As above, since the colored wafer back surface protective film is in astate where a thermosetting resin is uncured or partially cured evenwhen the film contains the thermosetting resin, the gel fraction of thecolored wafer back surface protective film is not particularlyrestricted but is, for example, suitably selected from the range of 50%by weight or less (0 to 50% by weight) and is preferably 30% by weightor less (0 to 30% by weight) and more preferably 10% by weight or less(0 to 10% by weight). The gel fraction of the colored wafer back surfaceprotective film can be measured by the following measuring method.

<Gel Fraction Measuring Method>

About 0.1 g of a sample is sampled from the colored wafer back surfaceprotective film and precisely weighed (Weight of Sample) and, after thesample is wrapped in a mesh-type sheet, is immersed in about 50 mL oftoluene at room temperature for 1 week. Thereafter, a solvent-insolublematter (content in the mesh-type sheet) is taken out of the toluene anddried at 130° C. for about 2 hours, a solvent-insoluble matter afterdrying is weighed (Weight after Immersion and Drying), and then the gelfraction (% by weight) is calculated according to the following equation(a).Gel Fraction(% by weight)=[(Weight after Immersion and Drying)/(Weightof Sample)]×100  (a)

Incidentally, the gel fraction of the colored wafer back surfaceprotective film can be controlled by the kind and content of the resincomponents, the kind and content of the crosslinking agent, heatingtemperature and heating time, and the like.

The colored wafer back surface protective film is a colored film-shapedarticle and the colored form is not particularly restricted. The coloredwafer back surface protective film may be, for example, a film-shapedarticle formed of a thermoplastic and/or thermosetting resin and a resincomposition containing a color agent and the like or may be afilm-shaped article having a constitution that a resin layer formed of aresin composition containing a thermoplastic resin and/or athermosetting resin and a coloring agent layer are laminated. Thecoloring agent layer is preferably formed of the colorant and a resincomposition containing a thermoplastic resin and/or a thermosettingresin.

In this regard, in the case that the colored wafer back surfaceprotective film is a laminate of the resin layer and the coloring agent,the colored wafer back surface protective film in the laminated formpreferably has a form where one resin layer, a coloring agent layer andanother resin layer are laminated in the order. In this case, two resinlayers at both sides of the coloring agent layer may be resin layershaving the same composition or may be resin layers having differentcomposition.

In the invention, in the case that the colored wafer back surfaceprotective film is a film-shaped article formed of a resin compositioncontaining a thermosetting resin such as an epoxy resin, closeadhesiveness to a semiconductor wafer can be effectively exhibited.

Incidentally, since cutting water is used in the dicing step of theworkpiece (semiconductor wafer), the colored wafer back surfaceprotective film absorbs moisture to have a moisture content of a normalstate or more in some cases. When flip chip bonding is performed withmaintaining such a high moisture content, water vapor remains at theclose adhesion interface between the colored wafer back surfaceprotective film and the workpiece or its processed body (chip-shapedworkpiece) and lifting is generated in some cases. Therefore, as thecolored wafer back surface protective film, the existence of a layercomposed of a core material having a high moisture transparency diffuseswater vapor and thus it becomes possible to avoid such a problem. Fromsuch a viewpoint, the colored wafer back surface protective film may beone in which the layer composed of the core material is laminated at itsone surface or both surfaces. Examples of the core material includefilms (e.g., polyimide films, polyester films, polyethyleneterephthalate films, polyethylene naphthalate films, polycarbonatefilms, etc.), resin substrates reinforced with a glass fiber or aplastic nonwoven fiber, and silicon substrate, and glass substrates.

The thickness of the colored wafer back surface protective film is notparticularly restricted but can be, for example, suitably selected fromthe range of 5 to 500 μm. In the invention, the thickness of the coloredwafer back surface protective film is preferably about 5 to 150 μm andmore preferably about 5 to 100 μm. The colored wafer back surfaceprotective film may have either form of a single layer and a laminatedlayer.

As the colored wafer back surface protective film in the invention, theelastic modulus (tensile storage elastic modulus E′) at 23° C. ispreferably 1 GPa or more, more preferably 2 GPa or more, and furtherpreferably 3 GPa or more. When the elastic modulus of the colored waferback surface protective film is 1 GPa or more, the attachment of thecolored wafer back surface protective film to the support can besuppressed or prevented at the time when the chip-shaped workpiece ispeeled from the pressure-sensitive adhesive layer of the dicing tapetogether with the colored wafer back surface protective film and thenthe colored wafer back surface protective film is placed on the supportto perform transportation and the like. In this regard, in the case thatthe colored wafer back surface protective film is formed of a resincomposition containing a thermosetting resin, as mentioned above, thethermosetting resin is usually in a uncured or partially cured state, sothat the elastic modulus of the colored wafer back surface protectivefilm at 23° C. is an elastic modulus at 23° C. in a state that thethermosetting resin is uncured or partially cured.

The elastic modulus (tensile storage elastic modulus E′) of the coloredwafer back surface protective film at 23° C. is determined by preparinga colored wafer back surface protective film without lamination onto thedicing tape and measuring elastic modulus in a tensile mode underconditions of a sample width of 10 mm, a sample length of 22.5 mm, asample thickness of 0.2 mm, a frequency of 1 Hz, and a temperatureelevating rate of 10° C./minute under a nitrogen atmosphere at aprescribed temperature (23° C.) using a dynamic viscoelasticitymeasuring apparatus “Solid Analyzer RS A2” manufactured by RheometricsCo. Ltd. and is regarded as a value of tensile storage elastic modulusE′ obtained.

The elastic modulus of the colored wafer back surface protective filmcan be controlled by the kind and content of the resin components(thermoplastic resin and/or thermosetting resin), the kind and contentof the filler such as silica filler, and the like.

Moreover, the light transmittance with a visible light (visible lighttransmittance, wavelength: 400 to 800 nm) in the colored wafer backsurface protective film is not particularly restricted but is, forexample, in the range of 20% or less (0 to 20%), preferably 10% or less(0 to 10%), and further preferably 5% or less (0 to 5%). When thecolored wafer back surface protective film has a visible lighttransmittance of 20% or less, the influence of the transmission of thelight on the semiconductor element is small.

The visible light transmittance (%) of the colored wafer back surfaceprotective film can be determined based on intensity change before andafter the transmittance of the visible light through the colored waferback surface protective film, the determination being performed bypreparing a colored wafer back surface protective film having athickness (average thickness) of 20 μm without lamination onto thedicing tape, irradiating the colored wafer back surface protective film(thickness: 20 μm) with a visible light having a wavelength of 400 to800 nm in a prescribed intensity, and measuring the intensity oftransmitted visible light using a trade name “ABSORPTION SPECTROPHOTOMETER” (manufactured by Shimadzu Corporation). In this regard, itis also possible to derive visible light transmittance (%; wavelength:400 to 800 nm) of the colored wafer back surface protective film havinga thickness of 20 μm from the value of the visible light transmittance(%; wavelength: 400 to 800 nm) of the colored wafer back surfaceprotective film whose thickness is not 20 μm. In the invention, thethickness (average thickness) of the colored wafer back surfaceprotective film at the time when the visible light transmittance (%) ofthe colored wafer back surface protective film is determined is 20 μmbut this thickness of the colored wafer back surface protective film isonly thickness at the time when the visible light transmittance (%) ofthe colored wafer back surface protective film is determined and may bethe same or different from the thickness of the colored wafer backsurface protective film in the dicing tape-integrated wafer back surfaceprotective film.

The visible light transmittance (%) of the colored wafer back surfaceprotective film can be controlled by the kind and content of the resincomponents, the kind and content of the coloring agent (such as pigmentor dye), the kind and content of the filer, and the like.

In the invention, the colored wafer back surface protective filmpreferably has a low moisture absorbance. Specifically, as the coloredwafer back surface protective film, the moisture absorbance when thefilm is allowed to stand under an atmosphere of temperature of 85° C.and humidity of 85% RH for 168 hours is preferably 1% by weight or lessand more preferably 0.8% by weight or less. By regulating the moistureabsorbance of the colored wafer back surface protective film (afterstanding under an atmosphere of temperature of 85° C. and humidity of85% RH for 168 hours) to 1% by weight or less, the laser marking abilitycan be enhanced. Moreover, for example, the generation of voids can besuppressed or prevented in the reflow step. The moisture absorbance ofthe colored wafer back surface protective film can be regulated, forexample, by changing the amount of the inorganic filler to be added. Themoisture absorbance (% by weight) of the colored wafer back surfaceprotective film is a value calculated from a weight change when the filmis allowed to stand under an atmosphere of temperature of 85° C. andhumidity of 85% RH for 168 hours. In the case that the colored waferback surface protective film is formed of a resin composition containinga thermosetting resin, the moisture absorbance of the colored wafer backsurface protective film is a value obtained when the film is allowed tostand under an atmosphere of temperature of 85° C. and humidity of 85%RH for 168 hours after thermal curing.

Moreover, in the invention, the colored wafer back surface protectivefilm preferably has a small ratio of volatile matter. Specifically, asthe colored wafer back surface protective film, the ratio of weightdecrease (weight decrease ratio) after heating at a temperature of 250°C. for 1 hour is preferably 1% by weight or less and more preferably0.8% by weight or less. By regulating the weight decrease ratio of thecolored wafer back surface protective film (after heating at atemperature of 250° C. for 1 hour) to 1% by weight or less, the lasermarking ability can be enhanced. Moreover, for example, the generationof cracks can be suppressed or prevented in the reflow step. The weightdecrease ratio of the colored wafer back surface protective film can beregulated, for example, by adding an inorganic substance capable ofreducing the crack generation at lead-free solder reflow, e.g., aninorganic filler such as silica or alumina. The weight decrease ratio (%by weight) of the colored wafer back surface protective film is a valuecalculated from a weight change when the film is heated at 250° C. for 1hour. In the case that the colored wafer back surface protective film isformed of a resin composition containing a thermosetting resin, theweight decrease ratio of the colored wafer back surface protective filmis a value obtained when the film is heated at 250° C. for 1 hour afterthermal curing.

The colored wafer back surface protective film is preferably protectedby a separator (releasable liner, not shown in figures). The separatorhas a function as a protective material for protecting the colored waferback surface protective film until it is practically used. Moreover, theseparator can be further used as a supporting base material at the timewhen the colored wafer back surface protective film is transferred tothe pressure-sensitive adhesive layer on the base material of the dicingtape. The separator is peeled when attaching a workpiece onto thecolored wafer back surface protective film of the dicing tape-integratedwafer back surface protective film. As the separator, a film ofpolyethylene or polypropylene, as well as a plastic film (polyethylenetelephthalate) or a paper whose surface is coated with a releasing agentsuch as a fluorine-based releasing agent or a long-chain alkylacrylate-based releasing agent can also be used. The separator can beformed by a conventionally known method. Moreover, the thickness or thelike of the separator is not particularly restricted.

(Dicing Tape)

The dicing tape is constituted by a base material and apressure-sensitive adhesive layer formed on the base material. Thus, thedicing tape sufficiently has a constitution that the base material andthe pressure-sensitive adhesive layer are laminated. The base material(supporting base material) can be used as a supporting material for thepressure-sensitive adhesive layer and the like. As the base material,for example, suitable thin materials, e.g., paper-based base materialssuch as paper; fiber-based base materials such as fabrics, non-wovenfabrics, felts, and nets; metal-based base materials such as metal foilsand metal plates; plastic base materials such as plastic films andsheets; rubber-based base materials such as rubber sheets; foamed bodiessuch as foamed sheets; and laminates thereof [particularly, laminates ofplastic based materials with other base materials, laminates of plasticfilms (or sheets) each other, etc.] can be used. In the invention, asthe base material, plastic base materials such as plastic films andsheets can be suitably employed. Examples of raw materials for suchplastic materials include olefinic resins such as polyethylene (PE),polypropylene (PP), and ethylene-propylene copolymers; copolymers usingethylene as a monomer component, such as ethylene-vinyl acetatecopolymers (EVA), ionomer resins, ethylene-(meth)acrylic acidcopolymers, and ethylene-(meth)acrylic acid ester (random, alternating)copolymers; polyesters such as polyethylene terephthalate (PET),polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT);acrylic resins; polyvinyl chloride (PVC); polyurethanes; polycarbonates;polyphenylene sulfide (PPS); amide-based resins such as polyamides(Nylon) and whole aromatic polyamides (aramide); polyether ether ketones(PEEK); polyimides; polyetherimides; polyvinylidene chloride; ABS(acrylonitrile-butadiene-styrene copolymers); cellulose-based resins;silicone resins; and fluorinated resins. Moreover, as the material ofthe base material, a polymer such as a cross-linked body of each of theabove resins can also be used. These raw materials may be employedsingly or in a combination of two or more kinds.

In the case where a plastic base material is used as the base material,deformation properties such as an elongation degree may be controlled bya stretching treatment or the like.

The thickness of the base material is not particularly restricted andcan be appropriately selected depending on strength, flexibility,intended purpose of use, and the like. For example, the thickness isgenerally 1000 μm or less (e.g., 1 to 1000 μm), preferably 1 to 500 μm,further preferably 3 to 300 μm, and particularly about 5 to 250 μm butis not limited thereto. In this regard, the base material may have anyform of a single layer form and a laminated layer form.

A commonly used surface treatment, e.g., a chemical or physicaltreatment such as a chromate treatment, ozone exposure, flame exposure,exposure to high-voltage electric shock, or an ionized radiationtreatment, or a coating treatment with an undercoating agent can beapplied in order to improve close adhesiveness with the adjacent layer,holding properties, etc.

Incidentally, the base material may contain various additives (acoloring agent, a filler, a plasticizer, an antiaging agent, anantioxidant, a surfactant, a flame retardant, etc.) within the rangewhere the advantages and the like of the invention are not impaired.

The pressure-sensitive adhesive layer is formed of a pressure-sensitiveadhesive and has pressure-sensitive adhesiveness. Such apressure-sensitive adhesive is not particularly restricted and can besuitably selected among known pressure-sensitive adhesives.Specifically, as the pressure-sensitive adhesive, a pressure-sensitiveadhesive having the above-mentioned characteristics can be suitablyselected and used among known pressure-sensitive adhesives such asacrylic pressure-sensitive adhesives, rubber-based pressure-sensitiveadhesives, vinyl alkyl ether-based pressure-sensitive adhesives,silicone-based pressure-sensitive adhesives, polyester-basedpressure-sensitive adhesives, polyamide-based pressure-sensitiveadhesives, urethane-based pressure-sensitive adhesives, fluorine-basedpressure-sensitive adhesives, styrene-diene block copolymer-basedpressure-sensitive adhesives, and creep characteristic-improvingpressure-sensitive adhesives in which a heat-meltable resin having amelting point of about 200° C. or lower is mixed into thesepressure-sensitive adhesives (see, e.g., JP-A-56-61468, JP-A-61-174857,JP-A-63-17981, JP-A-56-13040, etc.). Moreover, as the pressure-sensitiveadhesives, radiation-curable pressure-sensitive adhesives (or energyray-curable pressure-sensitive adhesives) or heat-expandablepressure-sensitive adhesives can be also used. The pressure-sensitiveadhesive may be employed singly or in a combination of two or morekinds.

In the invention, as the pressure-sensitive adhesive, acrylicpressure-sensitive adhesives and rubber-based pressure-sensitiveadhesives can be suitably used and particularly, acrylicpressure-sensitive adhesives are suitable. As the acrylicpressure-sensitive adhesives, there may be mentioned acrylicpressure-sensitive adhesives in which an acrylic polymer (homopolymer orcopolymer) using one or more alkyl (meth)acrylates ((meth)acrylic acidalkyl ester) as monomer components is used as the base polymer.

Examples of the alkyl (meth)acrylates in the above-mentioned acrylicpressure-sensitive adhesives include alkyl (meth)acrylates such asmethyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate,s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate,hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate,2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl(meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl(meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl(meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate,hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl(meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Asthe alkyl (meth)acrylates, alkyl (meth)acrylates having 4 to 18 carbonatoms are suitable. Incidentally, the alkyl group of the alkyl(meth)acrylate may be linear or branched.

The above-mentioned acrylic polymer may contain units corresponding toother monomer components (copolymerizable monomer components)polymerizable with the above-mentioned alkyl (meth)acrylates for thepurpose of modifying cohesive force, heat resistance, crosslinkingability, and the like. Examples of such copolymerizable monomercomponents include carboxyl group-containing monomers such as(meth)acrylic acid (acrylic acid or methacrylic acid), carboxyethylacrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaricacid, and crotonic acid; acid anhydride group-containing monomers suchas maleic anhydride and itaconic anhydride; hydroxyl group-containingmonomers such as hydroxyethyl (meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl(meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl(meth)acrylate, hydroxylauryl (meth)acrylate, and(4-hydroxymethylcyclohexyl)methyl methacrylate; sulfonic acidgroup-containing monomers such as styrenesulfonic acid, allylsulfonicacid, 2-(meth)acrylamide-2-methylpropanesulfonic acid,(meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and(meth)acryloyloxynaphthalenesulfonic acid; phosphoric acidgroup-containing monomers such as 2-hydroxyethylacryloyl phosphate;(N-substituted)amide-based monomers such as (meth)acrylamide,N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide,N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide;aminoalkyl (meth)acrylate-based monomers such as aminoethyl(meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, andt-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate-basedmonomers such as methoxyethyl (meth)acrylate and ethoxyethyl(meth)acrylate; cyanoacrylate monomers such as acrylonitrile andmethacrylonitrile; epoxy group-containing acrylic monomers such asglycidyl (meth)acrylate; styrene-based monomers such as styrene andα-methylstyrene; vinyl ester-based monomers such as vinyl acetate andvinyl propionate; olefin-based monomers such as isoprene, butadiene, andisobutylene; vinyl ether-based monomers such as vinyl ether;nitrogen-containing monomers such as N-vinylpyrrolidone,methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine,vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole,vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, andN-vinylcaprolactam; maleimide-based monomers such asN-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, andN-phenylmaleimide; itaconimide-based monomers such asN-methylitaconimide, N-ethylitaconimide, N-butylitaconimide,N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide,and N-laurylitaconimide; succinimide-based monomers such asN-(meth)acryloyloxymethylenesuccinimide,N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, andN-(meth)acryloyl-8-oxyoctamethylenesuccinimide; glycol-based acrylicester monomers such as polyethylene glycol (meth)acrylate, polypropyleneglycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, andmethoxypolypropylene glycol (meth)acrylate; acrylic acid ester-basedmonomers having a heterocycle, a halogen atom, a silicon atom, or thelike, such as tetrahydrofurfuryl (meth)acrylate, fluorine(meth)acrylate, and silicone (meth)acrylate; polyfunctional monomerssuch as hexanediol di(meth)acrylate, (poly)ethylene glycoldi(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentylglycol di(meth)acrylate, pentaerythritol di(meth)acrylate,trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate,dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyesteracrylate, urethane acrylate, divinylbenzene, butyl di(meth)acrylate, andhexyl di(meth)acrylate; and the like. These copolymerizable monomercomponents may be employed singly or in a combination of two or morekinds.

In the case that a radiation-curable pressure-sensitive adhesive (or anenergy ray-curable pressure-sensitive adhesive) is used as apressure-sensitive adhesive, examples of the radiation-curablepressure-sensitive adhesive (composition) include internalradiation-curable pressure-sensitive adhesives in which a polymer havinga radically reactive carbon-carbon double bond in the polymer side chainor main chain is used as the base polymer, radiation-curablepressure-sensitive adhesives in which a UV curable monomer component oroligomer component is blended into the pressure-sensitive adhesive, andthe like. Moreover, in the case that the heat-expandablepressure-sensitive adhesive is used as the pressure-sensitive adhesive,there may be mentioned heat-expandable pressure-sensitive adhesivescontaining a pressure-sensitive adhesive and a foaming agent(particularly, heat-expandable microsphere) and the like as theheat-expandable pressure-sensitive adhesive.

In the invention, the pressure-sensitive adhesive layer may containvarious additives (e.g., a tackifying resin, a coloring agent, athickener, an extender, a filler, a plasticizer, an antiaging agent, anantioxidant, a surfactant, a crosslinking agent, etc.) within the rangewhere the advantages of the invention are not impaired.

The crosslinking agent is not particularly restricted and knowncrosslinking agents can be used. Specifically, as the crosslinkingagent, not only isocyanate-based crosslinking agents, epoxy-basedcrosslinking agents, melamine-based crosslinking agents, andperoxide-based crosslinking agents but also urea-based crosslinkingagents, metal alkoxide-based crosslinking agents, metal chelate-basedcrosslinking agents, metal salt-based crosslinking agents,carbodiimide-based crosslinking agents, oxazoline-based crosslinkingagents, aziridine-based crosslinking agents, amine-based crosslinkingagents, and the like may be mentioned, and isocyanate-based crosslinkingagents and epoxy-based crosslinking agents are suitable. Specificexamples of the isocyanate-based crosslinking agents and the epoxy-basedcrosslinking agents include compounds (specific examples) specificallyexemplified in the paragraphs concerning the colored wafer back surfaceprotective film. The crosslinking agent may be employed singly or in acombination of two or more kinds. Incidentally, the amount of thecrosslinking agent is not particularly restricted.

In the invention, instead of the use of the crosslinking agent ortogether with the use of the crosslinking agent, it is also possible toperform the crosslinking treatment by irradiation with an electron beamor ultraviolet light.

The pressure-sensitive adhesive layer can be, for example, formed byutilizing a commonly used method including mixing a pressure-sensitiveadhesive and optional solvent and other additives and then shaping themixture into a sheet-like layer. Specifically, the pressure-sensitiveadhesive layer can be, for example, formed by a method includingapplying a mixture containing a pressure-sensitive adhesive and optionalsolvent and other additives on a base material, a method includingapplying the above-mentioned mixture on an appropriate separator (suchas a release paper) to form a pressure-sensitive adhesive layer and thentransferring (transcribing) it on a base material, or the like method.

The thickness of the pressure-sensitive adhesive layer is notparticularly restricted and, for example, is about 5 to 300 μm,preferably 5 to 80 μm, and more preferably 15 to 50 μm. When thethickness of the pressure-sensitive adhesive layer is within theabove-mentioned range, an appropriate pressure-sensitive adhesive forcecan be effectively exhibited. The pressure-sensitive adhesive layer maybe either a single layer or a multi layer.

According to the invention, the dicing tape-integrated wafer backsurface protective film can be made to have an antistatic function.Owing to this constitution, the circuit can be prevented from breakingdown owing to the generation of electrostatic energy at the time ofclose adhesion (adhesion) and at the time of peeling thereof or owing tocharging of a workpiece (a semiconductor wafer, etc.) by theelectrostatic energy. Imparting of the antistatic function can beperformed by an appropriate manner such as a method of adding anantistatic agent or a conductive substance to the base material, thepressure-sensitive adhesive layer, and the colored wafer back surfaceprotective film or a method of providing a conductive layer composed ofa charge-transfer complex, a metal film, or the like onto the basematerial. As these methods, a method in which an impurity ion having afear of changing quality of the semiconductor wafer is difficult togenerate is preferable. Examples of the conductive substance (conductivefiller) to be blended for the purpose of imparting conductivity,improving thermal conductivity, and the like include a sphere-shaped, aneedle-shaped, a flake-shaped metal powder of silver, aluminum, gold,copper, nickel, a conductive alloy, or the like; a metal oxide such asalumina; amorphous carbon black, and graphite. However, the coloredwafer back surface protective film is preferably non-conductive from theviewpoint of having no electric leakage.

In the invention, the dicing tape may be prepared as mentioned above andused or a commercially available product may be used.

Moreover, the dicing tape-integrated wafer back surface protective filmmay be formed in a form where it is wound as a roll or may be formed ina form where the sheet (film) is laminated. For example, in the casewhere the film has the form where it is wound as a roll, the film iswound as a roll in a state that the dicing tape-integrated wafer backsurface protective film is protected by a separator according to needs,whereby the film can be prepared as a dicing tape-integrated wafer backsurface protective film in a state or form where it is wound as a roll.In this regard, the dicing tape-integrated wafer back surface protectivefilm in the state or form where it is wound as a roll may be constitutedby the base material, the pressure-sensitive adhesive layer formed onone surface of the base material, the wafer back surface protective filmformed on the pressure-sensitive adhesive layer, and a releasablytreated layer (rear surface treated layer) formed on the other surfaceof the base material.

Incidentally, the thickness of the dicing tape-integrated wafer backsurface protective film (total thickness of the thickness of the waferback surface protective film and the thickness of the dicing tapecomposed of the base material and the pressure-sensitive adhesive layer)can be, for example, selected from the range of 11 to 300 μm and ispreferably 15 to 200 μm and more preferably 20 to 150 μm.

In the dicing tape-integrated wafer back surface protective film, theratio of the thickness of the wafer back surface protective film to thethickness of the pressure-sensitive adhesive layer of the dicing tape isnot particularly restricted but can be, for example, appropriatelyselected from the range of the thickness of the wafer back surfaceprotective film/the thickness of the pressure-sensitive adhesive layerof the dicing tape=150/5 to 3/100, and is preferably 100/5 to 3/50 andmore preferably 60/5 to 3/40. When the ratio of the thickness of thewafer back surface protective film to the thickness of thepressure-sensitive adhesive layer of the dicing tape is within the aboverange, an appropriate pressure-sensitive adhesive force can be exhibitedand excellent dicing property and picking-up property can be exhibited.

Moreover, in the dicing tape-integrated wafer back surface protectivefilm, the ratio of the thickness of the wafer back surface protectivefilm to the thickness of the dicing tape (total thickness of the basematerial and the pressure-sensitive adhesive layer) is not particularlyrestricted but can be, for example, appropriately selected from therange of the thickness of the wafer back surface protective film/thethickness of the dicing tape=150/50 to 3/500, and is preferably 100/50to 3/300 and more preferably 60/50 to 3/150. When the ratio of thethickness of the wafer back surface protective film to the thickness ofthe dicing tape is within the range of 150/50 to 3/500, a picking-upproperty is good and generation of lateral residue at dicing can besuppressed or prevented.

As above, by controlling the ratio of the thickness of the wafer backsurface protective film to the thickness of the pressure-sensitiveadhesive layer of the dicing tape or the ratio of the thickness of thewafer back surface protective film to the thickness of the dicing tape(total thickness of the base material and the pressure-sensitiveadhesive layer), a dicing property at the dicing step, a picking-upproperty at the picking-up step, and the like can be improved and thedicing tape-integrated wafer back surface protective film can beeffectively utilized from the dicing step of the semiconductor wafer tothe flip chip bonding step of the semiconductor chip.

(Producing Method of Dicing Tape-Integrated Wafer Back SurfaceProtective Film)

The producing method of the dicing tape-integrated wafer back surfaceprotective film of the invention is described while using the dicingtape-integrated wafer back surface protective film 1 as an example.First, the base material 31 can be formed by a conventionally knownfilm-forming method. Examples of the film-forming method include acalendar film-forming method, a casting method in an organic solvent, aninflation extrusion method in a closely sealed system, a T-die extrusionmethod, a co-extrusion method, and a dry laminating method.

Next, the pressure-sensitive adhesive layer 32 is formed by applying apressure-sensitive adhesive composition onto the base material 31,followed by drying (by crosslinking under heating according to needs).Examples of the application method include roll coating, screen coating,and gravure coating. In this regard, the application of thepressure-sensitive adhesive composition may be performed directly ontothe base material 31 to form the pressure-sensitive adhesive layer 32 onthe base material 31, or the pressure-sensitive adhesive composition maybe applied onto a release paper or the like whose surface has beensubjected to a releasable treatment to form a pressure-sensitive layer,which is then transferred onto the base material 31 to form thepressure-sensitive adhesive layer 32 on the base material 31. Thus, adicing tape 3 is prepared by forming the pressure-sensitive adhesivelayer 32 on the base material 31.

On the other hand, a coated layer is formed by applying a formingmaterial for forming the colored wafer back surface protective film 2onto a release paper so as to have a prescribed thickness after dryingand further drying under prescribed conditions (in the case that thermalcuring is necessary, performing a heating treatment and drying accordingto needs). The colored wafer back surface protective film 2 is formed onthe pressure-sensitive adhesive layer 32 by transferring the coatedlayer onto the pressure-sensitive adhesive layer 32. In this regard, thewafer back surface protective film 2 can be also formed on thepressure-sensitive adhesive layer 32 by directly applying the formingmaterial for forming the colored wafer back surface protective film 2onto the pressure-sensitive adhesive layer 32, followed by drying underprescribed conditions (in the case that thermal curing is necessary,performing a heating treatment and drying according to needs).Consequently, the dicing tape-integrated wafer back surface protectivefilm 1 according to the invention can be obtained. Incidentally, in thecase that thermal curing is performed at the formation of the coloredwafer back surface protective film 2, it is important to perform thethermal curing to such a degree that a partial curing is achieved butpreferably, the thermal curing is not performed.

The dicing tape-integrated wafer back surface protective film of theinvention can be suitably used at the production of a semiconductordevice including the flip chip bonding step. Namely, the dicingtape-integrated wafer back surface protective film of the invention isused at the production of a flip chip-mounted semiconductor device andthus the flip chip-mounted semiconductor device is produced in acondition or form where the colored wafer back surface protective filmof the dicing tape-integrated wafer back surface protective film isattached to the back surface of the semiconductor chip. Therefore, thedicing tape-integrated wafer back surface protective film of theinvention can be used for a flip chip-mounted semiconductor device (asemiconductor device in a state or form where the semiconductor chip isfixed to an adherend such as a substrate by a flip chip bonding method).

(Semiconductor Wafer)

The workpiece (semiconductor wafer) is not particularly restricted aslong as it is a known or commonly used semiconductor wafer and can beappropriately selected and used among semiconductor wafers made ofvarious materials. In the invention, as the semiconductor wafer, asilicon wafer can be suitable used.

(Production Process of Semiconductor Device)

The process for producing a semiconductor device of the invention is notparticularly restricted as long as it is a process for producing asemiconductor device using the dicing tape-integrated wafer back surfaceprotective film. For example, a production process including thefollowing steps and the like process may be mentioned:

a step of attaching a workpiece onto the colored wafer back surfaceprotective film of the dicing tape-integrated wafer back surfaceprotective film (mounting step);

a step of dicing the workpiece to form a chip-shaped workpiece (dicingstep);

a step of peeling the chip-shaped workpiece from the pressure-sensitiveadhesive layer of the dicing tape together with the colored wafer backsurface protective film (picking-up step); and

a step of fixing the chip-shaped workpiece to an adherend by flip chipbonding (flip chip bonding step).

More specifically, as the process for producing a semiconductor device,for example, a semiconductor device can be produced using the dicingtape-integrated wafer back surface protective film of the invention,after the separator optionally provided on the colored wafer backsurface protective film is appropriately peeled off, as follows.Hereinafter, referring to FIGS. 2A to 2D, the process is described whileusing the dicing tape-integrated wafer back surface protective film 1 asan example.

FIGS. 2A to 2D are cross-sectional schematic views showing oneembodiment of the process for producing a semiconductor device using thedicing tape-integrated wafer back surface protective film of theinvention. In FIGS. 2A to 2D, 4 is a workpiece (semiconductor wafer), 5is a chip-shaped workpiece (semiconductor chip), 51 is a bump formed atthe circuit face of the semiconductor chip 5, 6 is an adherend, 61 is aconductive material for conjugation adhered to a connecting pad of theadherend 6, and 1, 2, 3, 31, and 32 are respectively a dicingtape-integrated wafer back surface protective film, a colored wafer backsurface protective film, a dicing tape, a base material, and apressure-sensitive adhesive layer, as mentioned above.

(Mounting Step)

First, as shown in FIG. 2A, the semiconductor wafer (workpiece) 4 isattached (press-bonded) onto the colored wafer back surface protectivefilm 2 in the dicing tape-integrated wafer back surface protective film1 to fix the semiconductor wafer by close adhesion and holding (mountingstep). The present step is usually performed while pressing with apressing means such as a pressing roll.

(Dicing Step)

Next, as shown in FIG. 2B, the semiconductor wafer 4 is diced.Consequently, the semiconductor wafer 4 is cut into a prescribed sizeand individualized (is formed into small pieces) to producesemiconductor chips (chip-shaped workpiece) 5. The dicing is performedaccording to a normal method from the circuit face side of thesemiconductor wafer 4, for example. Moreover, the present step canadopt, for example, a cutting method called full-cut that forms a slitreaching the dicing tape-integrated wafer back surface protective film1. In the invention, it is important that the workpiece is fully cut(completely cut) in the dicing step. On this occasion, it is importantthat the workpiece is diced together with the colored wafer back surfaceprotective film while completely cutting the colored wafer back surfaceprotective film. Namely, it is important that the present step is a stepof forming a chip-shaped workpiece by dicing the workpiece together withthe colored wafer back surface protective film. In this regard, at thedicing of the workpiece together with the colored wafer back surfaceprotective film, the dicing can be performed in a form where a slit isnot formed on the dicing tape or in a form where a slit is formed atleast partially (preferably partially so that the dicing tape is notcut). The dicing apparatus used in the present step is not particularlyrestricted, and a conventionally known apparatus can be used. Further,since the semiconductor wafer 4 is adhered and fixed by the dicingtape-integrated wafer back surface protective film 1, chip crack andchip fly can be suppressed, as well as the damage of the semiconductorwafer can also be suppressed. In this regard, when the colored waferback surface protective film 2 is formed of a resin compositioncontaining an epoxy resin, generation of adhesive extrusion from thecolored wafer back surface protective film is suppressed or prevented atthe cut surface even when it is cut by dicing. As a result,re-attachment (blocking) of the cut surfaces themselves can besuppressed or prevented and thus the picking-up to be mentioned belowcan be furthermore conveniently performed.

In the case where the dicing tape-integrated wafer back surfaceprotective film is expanded, the expansion can be performed using aconventionally known expanding apparatus. The expanding apparatus has adoughnut-shaped outer ring capable of pushing the dicing tape-integratedwafer back surface protective film downward through a dicing ring and aninner ring which has a diameter smaller than the outer ring and supportsthe dicing tape-integrated wafer back surface protective film. Owing tothe expanding step, it is possible to prevent the damage of adjacentsemiconductor chips through contact with each other in the picking-upstep to be mentioned below.

(Picking-Up Step)

Picking-up of the semiconductor chip 5 is performed as shown in FIG. 2Cto peel the semiconductor chip 5 together with the colored wafer backsurface protective film 2 from the dicing tape 3 in order to collect thesemiconductor chip 5 that is adhered and fixed to the dicingtape-integrated wafer back surface protective film 1. The method ofpicking-up is not particularly restricted, and conventionally knownvarious methods can be adopted. For example, there may be mentioned amethod including pushing up each semiconductor chip 5 from the basematerial 31 side of the dicing tape-integrated wafer back surfaceprotective film 1 with a needle and picking-up the pushed semiconductorchip 5 with a picking-up apparatus. In this regard, the picked-upsemiconductor chip 5 is protected with the colored wafer back surfaceprotective film 2 at the back surface (also referred to as a non-circuitface, a non-electrode-formed face, etc.).

(Flip Chip Bonding Step)

The picked-up semiconductor chip 5 is fixed to an adherend such as abase material by a flip chip bonding method (flip chip mounting method).Specifically, the semiconductor chip 5 is fixed to the adherend 6according to a usual manner in a form where the circuit face (alsoreferred to as a front face, circuit pattern-formed face,electrode-formed face, etc.) of the semiconductor chip 5 is opposed tothe adherend 6. For example, the bump 51 formed at the circuit face ofthe semiconductor chip 5 is brought into contact with a conductivematerial 61 (such as solder) attached to a connecting pad of theadherend 6 and the conductive material is melted under pressing, wherebyelectric connection between the semiconductor chip 5 and the adherend 6can be secured and the semiconductor chip 5 can be fixed to the adherend6. In this regard, at the fixing of the semiconductor chip 5 to theadherend 6, it is important that the opposing faces of the semiconductorchip 5 and the adherend 6 and the gap are washed in advance and anencapsulating material (such as an encapsulating resin) is then filledinto the gap.

As the adherend, various substrates such as lead frames and circuitboards (such as wiring circuit boards) can be used. The material of thesubstrates is not particularly restricted and there may be mentionedceramic substrates and plastic substrates. Examples of the plasticsubstrates include epoxy substrates, bismaleimide triazine substrates,and polyimide substrates.

In the flip chip bonding, the material of the bump and the conductivematerial is not particularly restricted and examples thereof includesolders (alloys) such as tin-lead-based metal materials,tin-silver-based metal materials, tin-silver-copper-based metalmaterials, tin-zinc-based metal materials, and tin-zinc-bismuth-basedmetal materials, and gold-based metal materials and copper-based metalmaterials.

Incidentally, in the present step, the conductive material is melted toconnect the bump at the circuit face of the semiconductor chip 5 and theconductive material on the surface of the adherend 6. The temperature atthe melting of the conductive material is usually about 260° C. (e.g.,250° C. to 300° C.). The dicing tape-integrated wafer back surfaceprotective film of the invention can be made to have thermal resistancecapable of enduring the high temperature in the flip chip bonding stepby forming the wafer back surface protective film with an epoxy resin orthe like.

Moreover, the washing liquid to be used at washing the opposing face(electrode-formed face) between the semiconductor chip 5 and theadherend 6 in the flip chip bonding and the gap is not particularlyrestricted and the liquid may be an organic washing liquid or may be anaqueous washing liquid. The colored wafer back surface protective filmin the dicing tape-integrated wafer back surface protective film of theinvention has solvent resistance against the washing liquid and hassubstantially no solubility to these washing liquid. Therefore, asmentioned above, various washing liquids can be employed as the washingliquid and the washing can be achieved by any conventional methodwithout requiring any special washing liquid.

In the invention, the encapsulating material to be used at theencapsulation of the gap between the semiconductor chip 5 and theadherend 6 is not particularly restricted as long as the material is aresin having an insulating property (an insulating resin) and may besuitably selected and used among known encapsulating materials such asencapsulating resins. The encapsulating resin is preferably aninsulating resin having elasticity. Examples of the encapsulating resininclude resin compositions containing an epoxy resin. As the epoxyresin, there may be mentioned the epoxy resins exemplified in the above.Furthermore, the encapsulating resin composed of the resin compositioncontaining an epoxy resin may contain a thermosetting resin other thanan epoxy resin (such as a phenol resin) or a thermoplastic resin inaddition to the epoxy resin. Incidentally, a phenol resin can beutilized as a curing agent for the epoxy resin and, as such a phenolresin, there may be mentioned phenol resins exemplified in the above.

In the encapsulation step with the encapsulating resin, theencapsulating resin is usually cured by heating to achieveencapsulation. The curing of the encapsulating resin is usually carriedout at 175° C. for 60 to 90 seconds in many cases. However, in theinvention, without limitation thereto, the curing may be performed at atemperature of 165 to 185° C. for several minutes, for example. In thecase that the colored wafer back surface protective film is formed of aresin composition containing a thermosetting resin, the thermosettingresin constituting the colored wafer back surface protective film can becompletely or almost completely cured at the curing of the encapsulatingresin.

The distance of the gap between the semiconductor chip 5 and theadherend 6 is generally about 30 to 300 μm.

In the semiconductor device (flip chip mounted semiconductor device)produced using the dicing tape-integrated wafer back surface protectivefilm of the invention, since the colored wafer back surface protectivefilm is attached on the back surface of the chip-shaped workpiece,various markings can be applied with excellent visibility. Particularly,even when the marking method is a laser marking method, the marking canbe applied with an excellent contrast ratio and thus it is possible toobserve various kinds of information (literal information, graphicalinformation, etc.) applied by laser marking with a good visibility. Atthe laser marking, a known laser marking apparatus can be utilized.Moreover, as the laser, it is possible to utilize various lasers such asa gas laser, a solid-state laser, and a liquid laser. Specifically, asthe gas laser, any known gas lasers can be utilized without particularlimitation but a carbon dioxide laser (CO₂ laser) and an excimer laser(ArF laser, KrF laser, XeCl laser, XeF laser, etc.) are suitable. As thesolid-state laser, any known solid-state lasers can be utilized withoutparticular limitation but a YAG laser (such as Nd:YAG laser) and a YVO₄laser are suitable.

Since the flip chip mounted semiconductor device produced using thedicing tape-integrated wafer back surface protective film of theinvention is a semiconductor device mounted by the flip chip mountingmethod, the device has a thinned and miniaturized shape as compared witha semiconductor device mounted by a die-bonding mounting method. Thus,the flip chip mounted semiconductor devices can be suitably employed asvarious electronic devices and electronic parts or materials and membersthereof. Specifically, as the electronic devices in which the flipchip-mounted semiconductor devices of the invention are utilized, theremay be mentioned so-called “mobile phones” and “PHS”, small-sizedcomputers [so-called “PDA” (handheld terminals), so-called“notebook-sized personal computer”, so-called “Net Book (trademark)”,and so-called “wearable computers”, etc.], small-sized electronicdevices having a form where a “mobile phone” and a computer areintegrated, so-called “Digital Camera (trademark)”, so-called “digitalvideo cameras”, small-sized television sets, small-sized game machines,small-sized digital audio players, so-called “electronic notepads”,so-called “electronic dictionary”, electronic device terminals forso-called “electronic books”, mobile electronic devices (portableelectronic devices) such as small-sized digital type watches, and thelike. Needless to say, electronic devices (stationary type ones, etc.)other than mobile ones, e.g., so-called “desktop personal computers”,thin type television sets, electronic devices for recording andreproduction (hard disk recorders, DVD players, etc.), projectors,micromachines, and the like may be also mentioned. In addition,electronic parts or materials and members for electronic devices andelectronic parts are not particularly restricted and examples thereofinclude parts for so-called “CPU” and members for various memory devices(so-called “memories”, hard disks, etc.).

EXAMPLES

The following will illustratively describe preferred Examples of theinvention in detail. However, the materials, the mixing amount, and thelike described in these Examples are not intended to limit the scope ofthe invention to only those unless otherwise stated, and they are merelyexplanatory examples. Moreover, part in each example is a weightstandard unless otherwise stated.

Example 1

<Manufacture of Colored Wafer Back Surface Protective Film>

113 parts of an epoxy resin (trade name “EPICOAT 1004” manufactured byJER Co., Ltd.), 121 parts of a phenol resin (trade name “MILEX XLC-4L”manufactured by Mitsui Chemicals, Inc.), 246 parts of sphere silica(trade name “SO-25R” manufactured by Admatechs Co., Ltd., averageparticle diameter: 0.5 μm), 5 parts of a dye 1 (trade name “OIL GREEN502” manufactured by Orient Chemical Industries Co., Ltd.), and 5 partsof a dye 2 (trade name “OIL BLACK BS” manufactured by Orient ChemicalIndustries Co., Ltd.) based on 100 parts of an acrylic acid ester-basedpolymer (trade name “PARACRON W-197CM” manufactured by Negami ChemicalIndustrial Co., Ltd.) having ethyl acrylate and methyl methacrylate asmain components were dissolved into methyl ethyl ketone to prepare aresin composition solution having a solid concentration of 23.6% byweight.

The resin composition solution was applied onto a releasably treatedfilm as a releasable liner (separator) constituted of a polyethyleneterephthalate film having a thickness of 50 which had been subjected toa silicone-releasing treatment, and then dried at 130° C. for 2 minutesto manufacture a colored wafer back surface protective film A having athickness (average thickness) of 20 μm.

<Manufacture of Dicing Tape-Integrated Wafer Back Surface ProtectiveFilm>

The above colored wafer back surface protective film A was attached onthe pressure-sensitive adhesive layer of a dicing tape (trade name“V-8-T” manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 average thickness of pressure-sensitive adhesivelayer: 10 μm) using a hand roller to manufacture a dicingtape-integrated wafer back surface protective film.

Example 2

<Manufacture of Colored Wafer Back Surface Protective Film>

113 parts of an epoxy resin (trade name “EPICOAT 1004” manufactured byJER Co., Ltd.), 121 parts of a phenol resin (trade name “MILEX XLC-4L”manufactured by Mitsui Chemicals, Inc.), 246 parts of sphere silica(trade name “SO-25R” manufactured by Admatechs Co., Ltd., averageparticle diameter: 0.5 μm), 10 parts of a dye 1 (trade name “OIL GREEN502” manufactured by Orient Chemical Industries Co., Ltd.), and 10 partsof a dye 2 (trade name “OIL BLACK BS” manufactured by Orient ChemicalIndustries Co., Ltd.) based on 100 parts of an acrylic acid ester-basedpolymer (trade name “PARACRON W-197CM” manufactured by Negami ChemicalIndustrial Co., Ltd.) having ethyl acrylate and methyl methacrylate asmain components were dissolved into methyl ethyl ketone to prepare aresin composition solution having a solid concentration of 23.6% byweight.

The resin composition solution was applied onto a releasably treatedfilm as a releasable liner (separator) constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to manufacture a colored wafer back surface protective film Bhaving a thickness (average thickness) of 20 μm.

<Manufacture of Dicing Tape-Integrated Wafer Back Surface ProtectiveFilm>

The above colored wafer back surface protective film B was attached onthe pressure-sensitive adhesive layer of a dicing tape (trade name“V-8-T” manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) using a hand roller to manufacture a dicingtape-integrated wafer back surface protective film.

Example 3

<Manufacture of Colored Wafer Back Surface Protective Film>

32 parts of an epoxy resin (trade name “EPICOAT 1004” manufactured byJER Co., Ltd.), 35 parts of a phenol resin (trade name “MILEX XLC-4L”manufactured by Mitsui Chemicals, Inc.), 90 parts of sphere silica(trade name “SO-25R” manufactured by Admatechs Co., Ltd., averageparticle diameter: 0.5 μm), 3 parts of a dye 1 (trade name “OIL GREEN502” manufactured by Orient Chemical Industries Co., Ltd.), and 3 partsof a dye 2 (trade name “OIL BLACK BS” manufactured by Orient ChemicalIndustries Co., Ltd.) based on 100 parts of an acrylic acid ester-basedpolymer (trade name “PARACRON W-197CM” manufactured by Negami ChemicalIndustrial Co., Ltd.) having ethyl acrylate and methyl methacrylate asmain components were dissolved into methyl ethyl ketone to prepare aresin composition solution having a solid concentration of 23.6% byweight.

The resin composition solution was applied onto a release-treated filmas a releasable liner (separator) constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to manufacture a colored wafer back surface protective film Chaving a thickness (average thickness) of 20 μm.

<Manufacture of Dicing Tape-Integrated Wafer Back Surface ProtectiveFilm>

The above colored wafer back surface protective film C was attached onthe pressure-sensitive adhesive layer of a dicing tape (trade name“V-8-T” manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) using a hand roller to manufacture a dicingtape-integrated wafer back surface protective film.

Incidentally, in the dicing tape-integrated wafer back surfaceprotective films according to Examples 1 to 3, the thickness (averagethickness) of the colored wafer back surface protective film is 20 μm.Moreover, with regard to the dicing tape (trade name “V-8-T”manufactured by Nitto Denko Corporation), the thickness (averagethickness) of the base material is 65 μm, the thickness (averagethickness) of the pressure-sensitive adhesive layer is 10 μm, and thetotal thickness is 75 μm. Therefore, in the dicing tape-integrated waferback surface protective films according to Examples 1 to 3, the ratio ofthe thickness of the colored wafer back surface protective film to thethickness of the pressure-sensitive adhesive layer of the dicing tape(thickness of the colored wafer back surface protective film/thicknessof the pressure-sensitive adhesive layer of the dicing tape; ratio inaverage thickness) is 20/10 and the ratio of the thickness of thecolored wafer back surface protective film to the thickness of thedicing tape (total thickness of the base material and thepressure-sensitive adhesive layer) (thickness of the colored wafer backsurface protective film/thickness of the dicing tape; ratio in averagethickness) is 20/75.

(Evaluation 1: Measurement of Physical Properties of Wafer Back SurfaceProtective Film)

With regard to the wafer back surface protective films (colored waferback surface protective films) in the dicing tape-integrated wafer backsurface protective films manufactured in Examples 1 to 3, visible lighttransmittance (%), moisture absorbance (% by weight), and weightdecrease ratio (% by weight) were measured. The results of themeasurement are shown in Table 1.

<Measuring Method of Visible Light Transmittance>

Each of the colored wafer back surface protective films manufactured inExamples 1 to 3 (colored wafer back surface protective films A to C)(thickness: 20 μm) was irradiated with a visible light having awavelength of 400 nm to 800 nm at a prescribed intensity using a tradename “ABSORPTION SPECTRO PHOTOMETER” (manufactured by ShimadzuCorporation) and intensity of the transmitted visual light was measured.From the intensity change of the visible light before and after passedthrough the colored wafer back surface protective film, the visiblelight transmittance (%) was determined.

<Measuring Method of Moisture Absorbance>

Each of the colored wafer back surface protective films manufactured inExamples 1 to 3 (colored wafer back surface protective films A to C) wasallowed to stand in a constant-temperature and constant-humidity chamberat a temperature of 85° C. and a humidity of 85% RH for 168 hours. Fromthe weight change before and after standing, moisture absorbance (% byweight) was determined.

<Measuring Method of Weight Decrease Ratio>

Each of the colored wafer back surface protective films manufactured inExamples 1 to 3 (colored wafer back surface protective films A to C) wasallowed to stand in a drying machine at 250° C. for 1 hour. From theweight change (amount of weight decrease) before and after the standing,a weight decrease ratio (% by weight) was determined.

(Evaluation 2)

Moreover, on the dicing tape-integrated wafer back surface protectivefilms manufactured in Examples 1 to 3, elastic modulus of the coloredwafer back surface protective films, a dicing property, a picking-upproperty, a flip chip bonding property, a marking property of the waferback surface, and an appearance property of the wafer back surface wereevaluated or measured by the following evaluating or measuring methods.The results of the evaluation or measurement are described in Table 2all together.

<Measuring Method for Elastic Modulus of Colored Wafer Back SurfaceProtective Film>

The elastic modulus of the colored wafer back surface protective filmwas determined by preparing a colored wafer back surface protective filmwithout lamination onto the dicing tape and measuring elastic modulus ina tensile mode under conditions of a sample width of 10 mm, a samplelength of 22.5 mm, a sample thickness of 0.2 mm, a frequency of 1 Hz,and a temperature elevating rate of 10° C./minute under a nitrogenatmosphere at a prescribed temperature (23° C.) using a dynamicviscoelasticity measuring apparatus “Solid Analyzer RS A2” manufacturedby Rheometrics Co. Ltd., and was regarded as a value of tensile storageelastic modulus E′ obtained.

<Evaluation Method of Dicing Property/Picking-Up Property>

Using each of the dicing tape-integrated wafer back surface protectivefilms of Examples 1 to 3, the dicing property was evaluated by actuallydicing a semiconductor wafer and then peeling ability was evaluated,each evaluation being regarded as evaluation of dicing performance orpicking-up performance of the dicing tape-integrated wafer back surfaceprotective film.

A semiconductor wafer (diameter: 8 inches, thickness: 0.6 mm; a siliconmirror wafer) was subjected to a back surface polishing treatment and amirror wafer having a thickness of 0.2 mm was used as a workpiece. Afterthe separator was peeled from the dicing tape-integrated wafer backsurface protective film, the mirror wafer (workpiece) was attached ontothe colored wafer back surface protective film by roller press-bondingat 70° C. and dicing was further performed. Herein, the dicing wasperformed as full cut so as to be a chip size of 10 mm square. In thisregard, conditions for semiconductor wafer grinding, attachingconditions, and dicing conditions are as follows.

(Conditions for Semiconductor Wafer Grinding)

Grinding apparatus: trade name “DFG-8560” manufactured by DISCOCorporation

Semiconductor wafer: 8 inch diameter (back surface was ground so as tobe until a thickness of 0.2 mm from a thickness of 0.6 mm)

(Attaching Conditions)

Attaching apparatus: trade name “MA-3000II” manufactured by Nitto SeikiCo., Ltd.

Attaching speed: 10 mm/min

Attaching pressure: 0.15 MPa

Stage temperature at the time of attaching: 70° C.

(Dicing Conditions)

Dicing apparatus: trade name “DFD-6361” manufactured by DISCOCorporation

Dicing ring: “2-8-1” (manufactured by DISCO Corporation)

Dicing speed: 30 mm/sec

Dicing blade:

Z1; “2030-SE 27HCDD” manufactured by DISCO Corporation

Z2; “2030-SE 27HCBB” manufactured by DISCO Corporation

Dicing blade rotation speed:

Z1; 40,000 r/min

Z2; 45,000 r/min

Cutting method: step cutting

Wafer chip size: 10.0 mm square

In the dicing, it was confirmed whether the mirror wafer (workpiece) wasfirmly held on the dicing tape-integrated wafer back surface protectivefilm without peeling to effect the dicing satisfactory or not. The casewhere the dicing was well performed was ranked “Good” and the case wherethe dicing was not well performed was ranked “Poor”, thus the dicingability being evaluated.

Next, the chip-shaped workpiece obtained by dicing was peeled from thepressure-sensitive adhesive layer of the dicing tape together with thecolored wafer back surface protective film by pushing up the workpiecefrom the dicing tape side of the dicing tape-integrated wafer backsurface protective film with a needle, whereby the chip-shaped workpiecein a state where the back surface had been protected with the coloredwafer back surface protective film was picked up. The picking-up ratio(%) of the chips (400 pieces in total) on this occasion was determinedto evaluate the picking-up property. Therefore, the picking-up propertyis better when the picking-up ratio is closer to 100%.

Here, the picking-up conditions are as follows.

(Picking-Up Conditions for Semiconductor Wafer)

Picking-up apparatus: trade name “SPA-300” manufactured by Shinkawa Co.,Ltd.

Number of picking-up needles: 9 needles

Pushing-up speed of needle: 20 mm/s

Pushing-up distance of needle: 500 μm

Picking-up time: 1 second

Dicing tape-expanding amount: 3 mm

<Evaluation Method for Flip Chip Bonding Property>

On the chip-shaped workpiece according to each Example obtained by theabove-mentioned <Evaluation method of dicing properties/picking-upproperty> using the dicing tape-integrated wafer back surface protectivefilm according to each of Example, a bump formed at the circuit face ofthe chip-shaped workpiece was brought into contact with a conductivematerial (solder) attached to a connecting pad of the circuit board in aform where the surface (circuit face) of the chip-shaped workpiece wasopposed to the surface of the circuit board possessing a wiringcorresponding to the circuit face, and the conductive material wasmelted under pressure by raising the temperature to 260° C. and thencooled to room temperature, whereby the chip-shaped workpiece was fixedto the circuit board to manufacture a semiconductor device. The flipchip bonding property on this occasion was evaluated according to thefollowing evaluation standard.

(Evaluation Standard for Flip Chip Bonding Property)

Good: Mounting can be achieved by the flip chip bonding method with notrouble;

Bad: Mounting cannot be achieved by the flip chip bonding method.

<Evaluation Method for Marking Property of Wafer Back Surface>

Laser marking was applied on the back surface of the chip-shapedworkpiece (i.e., the front face of the colored wafer back surfaceprotective film) in the semiconductor device obtained by theabove-mentioned <Evaluation method for flip chip bonding property>. Onthe information obtained by the laser marking (bar-code information),the laser marking ability of the semiconductor device obtained using thedicing tape-integrated wafer back surface protective film according toeach Example was evaluated according to the following evaluationstandard.

(Evaluation Standard for Laser Marking Ability)

Good: The number of persons who judge the information obtained by thelaser marking satisfactorily visible is 8 persons or more among randomlyselected 10 adult persons;

Bad: The number of persons who judge the information obtained by thelaser marking satisfactorily visible is 7 persons or less among randomlyselected 10 adult persons.

<Evaluation Method for Appearance Property of Wafer Back Surface>

On the chip-shaped workpiece according to each Example obtained by theabove-mentioned <Evaluation method of dicing property/picking-upproperty> using the dicing tape-integrated wafer back surface protectivefilm according to each Example, the appearance property of the backsurface of the chip-shaped workpiece was visually evaluated according tothe following evaluation standard.

(Evaluation Standard for Appearance Properties>

Good: No peeling (lifting) is observed between the back surface of thewafer (silicon wafer) and the colored wafer back surface protective filmin the chip-shaped workpiece;

Bad: Peeling (lifting) is observed between the back surface of the wafer(silicon wafer) and the colored wafer back surface protective film inthe chip-shaped workpiece.

TABLE 1 Wafer back Moisture Weight surface Visible light absorbancedecrease protective transmittance (% by ratio (% film (%) weight) byweight) Example 1 Colored wafer 2 0.4 0.7 back surface protective film AExample 2 Colored wafer 1 0.4 0.9 back surface protective film B Example3 Colored wafer 12 0.5 0.7 back surface protective film C

TABLE 2 Tensile storage elastic Picking- Flip chip Laser Appear- modulusDicing up bonding marking ance E′ (23° C.) property property propertyability property Example 1 3 GPa Good 100% Good Good Good Example 2 3GPa Good 100% Good Good Good Example 3 1 GPa Good 100% Good Good Good

From Table 2, it was confirmed that the dicing tape-integrated waferback surface protective film according to Examples 1 to 3 possessed afunction as a dicing tape and a function as a wafer back surfaceprotective film at excellent levels.

Since a dicing tape and a wafer back surface protective film are formedin an integrated fashion in the dicing tape-integrated wafer backsurface protective film of the invention as well as the wafer backsurface protective film is colored, the dicing tape-integrated waferback surface protective film can be utilized from the dicing step of asemiconductor wafer to the flip chip bonding step of a semiconductorchip. Namely, the dicing tape-integrated wafer back surface protectivefilm of the invention can be suitably used as a dicing tape-integratedwafer back surface protective film possessing both functions of a dicingtape and a wafer back surface protective film at the production ofsemiconductor devices by a flip chip bonding method.

While the present invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the scope thereof.

This application is based on Japanese patent application No. 2009-020460filed Jan. 30, 2009 and Japanese patent application No. 2009-251125filed Oct. 30, 2009, the entire contents thereof being herebyincorporated by reference.

Further, all references cited herein are incorporated in theirentireties.

What is claimed is:
 1. A dicing tape-integrated wafer back surfaceprotective film comprising: a dicing tape comprising a base material anda pressure-sensitive adhesive layer formed on the base material; and awafer back surface protective film formed on the pressure-sensitiveadhesive layer of the dicing tape, wherein the wafer back surfaceprotective film is colored, and wherein the wafer back surfaceprotective film has a moisture absorbance of 1% by weight or less afterthe wafer back surface protective film is allowed to stand under anatmosphere of a temperature of 85° C. and a humidity of 85% RH for 168hours.
 2. The dicing tape-integrated wafer back surface protective filmaccording to claim 1, wherein said colored wafer back surface protectivefilm has a laser marking ability.
 3. The dicing tape-integrated waferback surface protective film according to claim 1, which is used for aflip chip-mounted semiconductor device.
 4. A process for producing asemiconductor device using a dicing tape-integrated wafer back surfaceprotective film, said process comprising steps of: attaching a workpieceonto said colored wafer back surface protective film of the dicingtape-integrated wafer back surface protective film according to claim 1,dicing the workpiece to form a chip-shaped workpiece, peeling thechip-shaped workpiece from the pressure-sensitive adhesive layer of thedicing tape together with said colored wafer back surface protectivefilm, and fixing the chip-shaped workpiece to an adherend by flip chipbonding.
 5. A flip chip-mounted semiconductor device, which ismanufactured using the dicing tape-integrated wafer back surfaceprotective film according to claim 1, said semiconductor devicecomprising a chip-shaped workpiece and the wafer back surface protectivefilm of the dicing tape-integrated wafer back surface protective filmattached to a back surface of the chip-shaped workpiece.